ocr: INPUT/OUTPUT EDGE DETECT CAPABILITY Bidirectional 1/0 Ports There is an asynchronous edge detect capability on The 6500/ provides four 8-bit input/ output ports (PA, two o' tne Port A 1/O 'ires. This capability exists in PB.PC. ard PD). Associated with the VO ports are four addition to and independently from the ncrmal Port AI/O 8-bit registers located on page zero. See the sysiem functions. The maximum rate at which an edge can be merrory map for soocific addresses Each 1/0 lire is detectec is one-half the 22 clock rate. The edge detect indivicualy selectable as an input or an output witnout ...
